Exercise as it relates to Disease/Strategies to increase physical activities in youth sedentary behaviour

This is a critic of how does the sedentary behaviours influenced physical activities. This critic was used as an university assignment for the University of Canberra for the unit: Health, Disease and Exercise.

Topic of the paper is "Physical Activity as a Substitute for Sedentary Behaviour in Youth"

Background
Sedentary behaviour is now indicated as an important risk factor for overweight/obesity and cardiometabolic disease, and nowadays teenagers are more likely to be sedentary rather than physically active.

What is Sedentary Behaviour? For example watching television, driving, reading books, recreational computer usage etc. But sleeping is generally not included in sedentary behaviour.
 * Energy expenditure ≤1.5 Metabolic Equivalents (METs) while in a sitting or reclining position.
 * The amount of time spent at low activity count on an accelerometer (<100 counts/min).

There is a theory to help people understanding how youth would spend their leisure time and how do their choices affect energy balance behaviours, it is called behavioural economics. In behavioural economic theory, activities can influence each other, if and when the rate of one decreases, the rate of another increase.

In this study, they are going to use behavioural economics methods to explore how experimental changes in a number of sedentary behaviours influenced by physical activity. Also to identify variables that differentiate between those who may substitute physical activity as sedentary behaviours are increased and those when sedentary behaviours are decreased.

Where is the research from?
Leonard H. Epstein, James N. Roemmich and Rocco A. Paluch from University at Buffalo, also Hollie A. Raynor from Brown University. It was conducted in a journal of the Society of BehavioralMedicine in 2005 called "Annals of Behavioural Medicine". This journal is focusing on basic and applied research in the interdisciplinary field of behavioural medicine.

What kind of research was this?
This was a quantitative research. Quantitative research is a method to quantify the problem by way of generating numerical data or data that can be transformed into usable statistics. It is used to quantify variables to generalise results from a large group of subject, such as
 * Attitudes
 * Opinions
 * Behaviours

What did the research involve?
This study involved 58 youth from 8 to 16 years of age, with 28 male and 30 female. They were recruited by newspaper advertisement.

They had to complete three phases of lifestyle. Each phase was lasting for 3 weeks. During the 9 weeks experiment, participant had to wear the accelerometer and keeping the sedentary behaviour logs.
 * 1) Baseline - maintain their usual pattern of sedentary behaviour, physical activity and energy intake.
 * 2) Increasing phase - increase 25-50% of sedentary behaviour base on the baseline phase.
 * 3) Decreasing phase - decrease 25-50% of sedentary behaviour base on the baseline phase.

What were the results?
The results were manipulated as planned.

Sedentary Behaviour Physical Activity had no change in Decrease Phase, but it decreased in Increase Phase. There was a slightly difference between boys and girls. Not surprised that, participants who decreased physical activity when targeted sedentary behaviour was increased were more obese.

Likewise, 24% of the participant (14 of 58) showed a symmetrical relationship between physical activity and targeted sedentary behaviours. Which means, when physical activities were increased, the sedentary behaviour decrease.

What conclusions can we take from this research?
This research has shown that during the phase when participants were asked to be more sedentary, girls made a significant increase in targeted sedentary behaviour than boys. This result was similar to a previous research conducted by Epstein in 2001, boys lose more weight than girls when they were assigned to reduce sedentary behaviour. This may be an important risk factor which explained why there was more obesity in adolescent girls. Moreover, 76% of participants showed an asymmetrical relationship between physical activity and sedentary behaviour. They were more likely to appearance larger increases in physical activity when the level of physical activity is lower. This suggested that the amount of physical activity may inhibit by the level of physical activity and obviously the reduction in sedentary behaviour will be associated with an increase in physical activity.

Further directions from this reasech
There are three directions that this research can go.
 * 1) The 3 weeks manipulations are comparatively brief, a longer period of manipulation may provide a more solid test result of how sedentary behaviour can influence physical activity.
 * 2) Although the result shows that there is no difference in age, however studying a wider range of age group may give us a better outcome to show how the teenagers allocate time among sedentary and active alternative.
 * 3) The order of increasing phase and decreasing phase in this research are not restricted, but it may affects the result significantly. For example, participants who decided to complete the decreasing phase first may create an active lifestyle habit in 3 weeks. This may affect the 3 weeks decreasing phase afterward as their habit had already changed.